1. Field of the Invention
The present invention relates to an orthopaedic implant assembly, and, more particularly, to an acetabular cup assembly used during hip replacement surgery.
2. Description of the Related Art
An orthopaedic implant assembly in the form of an acetabular cup assembly is implanted within a prepared acetabulum of a patient and receives the femoral head of a femoral implant. The acetabular cup includes an outside diameter which is placed against the prepared pelvis and an inside diameter which receives the femoral head. A polymeric bearing surface may be disposed at the inside diameter of the cup because of improved wear and reduced friction properties associated therewith.
An acetabular cup may include a portion defining an annular face or rim radially adjacent to the femoral head receiving cavity which is either formed from metal or plastic. Forming the rim from a plastic material has an advantage of preventing metal-to-metal contact between the neck of the femoral implant and the rim when the femoral implant is articulated within the acetabular cup. On the other hand, a metal rim is more rigid and allows secondary fixation devices such as bone screws to be placed through flanges or straps which project radially from the cup. Regardless of whether the rim surrounding the femoral head receiving cavity is formed from metal or plastic, the acetabular cup is formed as a unitary structure which is then implanted into a prepared acetabulum in the patient. The surgeon is not given a choice of whether to use the cup portion with a metal rim or a plastic rim surrounding the femoral head receiving cavity.
What is needed in the art is an acetabular cup with modular components allowing the surgeon to choose either a metal rim or a plastic rim surrounding the femoral head receiving cavity immediately prior to implantation into a prepared acetabulum, thereby allowing the surgeon to optimize the configuration of the implanted acetabular cup during surgery.